first,,,on another forum i lead a topic "Reef-safe* everything in a tank has an asterick. many retailers have to put a disclaimer on things today due to people moaning and griping..that Xcritter ate Ycritter, you said it was safe. therefore blanket statements "with caution".
so enough of that debate~
i have a pair of BT Trigs in my 210. model citizens. i have chromis in the tank and they actually watch the chromis for a safety factor...they see the chromis dart quickly,,they run to their cave. many fish use this technique, its called dither fish. when it comes to corals and clams, BT are safe, its not in their natural diet. shrimp, crabs and even the occational urchin, these are natural prey for them.
they are an active swimmer so a good current is needed for them. if you want them to have fun, have a strong cross tank current and watch them swim in it like a treadmill workout. they are hungry fish and need good food and chunky. mine get chunks of shrimp something they can chew on. mysis and such just wont fill them up. the only drawback with these fish in a reeftank in my opinion is because they need alot of food,,,yup, they poop alot.
i also have a Harlequin tusk,,,another fish many say do not belong in a reef, but after seeing my success others now have them without any negatives.
coloration, males will lose the yellow without a female. it will fade to almost grey similar to a females coloring.